Kaposi's sarcoma (KAP-o-seez sar-KO-ma): A type of cancer characterized by the abnormal growth of blood vessels that develop into skin lesions or occur internally.

Karenitecin: A drug being studied in the treatment of cancer. It belongs to a family of drugs called topoisomerase inhibitors. It is related to the anticancer drug camptothecin.

Karnofsky Performance Status: KPS. A standard way of measuring the ability of cancer patients to perform ordinary tasks. The scores range from 0 to 100, with a higher score indicating a better ability to carry out daily activities. KPS may be used to determine a patient's prognosis, to measure changes in functioning, or to decide if a patient could be included in a clinical trial.

Keloid (KEY-loyd): A type of scar, which depending on its maturity, is composed of mainly either type III (early) or type I (late) collagen. It is a result of an overgrowth of granulation tissue (collagen type 3) at the site of a healed skin injury which is then slowly replaced by collagen type 1. Keloids are firm, rubbery lesions or shiny, fibrous nodules, and can vary from pink to flesh-coloured or red to dark brown in colour.

Keratan sulfate: A glycosame.

Keratinocyte growth factor: A substance that stimulates the growth of epithelial cells that line the surface of the mouth; a noncancerous, rapidly growing skin tumor that usually occurs on sun-exposed areas of the skin and that can go away without treatment.

Keratoacanthoma (KER-a-toe-AK-an-THOW-ma): A benign (noncancerous), rapidly growing skin tumor that usually occurs on sun-exposed areas of the skin and that can go away without treatment.

Ketoconazole: A drug that treats infection caused by a fungus. It is also used as a treatment for prostate cancer because it can block the production of the male sex hormone.

Ketorolac: A drug that belongs to a family of drugs called nonsteroidal anti-inflammatory agents. It is being studied in cancer prevention.

Keyhole limpet hemocyanin: KLH. An extremely large, heterogeneous glycosylated protein consisting of subunits with a molecular weight of 350,000 and 390,000 in aggregates with molecular weights of 4,500,000-13,000,000. Each domain of a KLH subunit contains two copper atoms that together bind a single oxygen molecule (O2).

Killer cells: White blood cells that attack tumor cells and body cells that have been invaded by foreign substances.